Turkish Journal of Fisheries and Aquatic Sciences 8: 125-132 (2008) Life- History Traits and Decadal Trends in the Growth Parameters of Golden Mahseer Tor putitora (Hamilton 1822) from the Himalayan Stretch of the Ganga River System Prakah Nautiyal1,*, Anees Fatma Rizvi2, P. Dhasmanaa1 1 H N B Garhwal University, Department of Zoology, Srinagar, 246174, India. 2 Institute of Applied Sciences, Allahabad 211002, India. * Corresponding Author: Tel.: -; Fax: -; Received 07 August 2006 E-mail: [email protected]; ribbonfish123@ rediffmail.com Accepted 12 March 2008 Abstract Life-history traits such as age and body growth patterns of Tor putitora (Hamilton 1822), inhabiting the lesser Himalayan stretch of the Ganga river system in the Garhwal region were examined during 1994 and 1995. The maximum age was recorded to 17+ whereas harvestable size was 65.6 cm. The asymptotic length (L∞) exhibited a relative decline from 272 cm (K = 0.035 year-1) in 1980-81 to 216 cm (K = 0.041 year-1) in 1994-95 resulting in the corresponding increase of the growth coefficient (K). The total, natural and fishing mortality coefficients also exhibited a similar pattern 0.366, 0.054 and 0.312 and 0.58, 0.063, 0.517 year-1, respectively during 1980-81 and 1994-95. This was reflected in the exploitation rate and -1 ratio also, 0.376 and 0.852 and 0.7 and 0.891 year respectively for 1980-81 and 1994-95 Key words: age, growth, asymptotic length, mortality, exploitation, decadal trends. Introduction descend as the floods subside. T. putitora thus exhibits a tri-phased migration (Nautiyal and Lal, Desai (2003) has listed 10 valid species of 1984; Nautiyal, 2002). mahseer from Pakistan, India, China and Southeast Among the various species of Mahseer in India Asia, though more species have been listed recently T. putitora, familiarly known as the Golden or (Annexure 1). Dwivedi (2002) is of the opinion that Himalayan mahseer attains the largest size, 275 cm (9 the members of this group are found in rivers in the ft) in length and 54 kg (118 lb) in weight (Talwar and northern Plains of India and extend towards west Jhingran, 1991; Wikipedia, 2006). The size was through the river Indus in Pakistan and Euphrates and recorded by Hamilton in 1822. The first author (PN) Tigris in Iraq and to north in China. A number of recorded a size of 137.7 cm in 1980-81. Owing to its species are found in the southeast also (Kiat, 2004). size, golden colour, beautiful appearance and flavour, Annexure 2 lists the countries and their locations the fish is exploited thereby constituting an important compatible with distributional range of the Golden fishery along the Himalayan foothills. Exploitation as mahseer. It has been introduced in the southeast as far well as other factors (Nautiyal, 1984, 1989, 1990, as New Papua Guinea. Mahseer is a spectacular game 1994) has led to a decline in numbers in the fish and it constitutes main fishery in the Sivalik Himalayan stretch of the Ganga. The following Himalaya and uplands of the Deccan Plateau. Three observation supports this view, “Qasim and Qayyum species of the genus Tor occur in the Himalaya, Tor (1961) studied the breeding biology of T. putitora putitora, T. tor and T. progenius, the former is from the Ganga near Aligarh (far downstream of the prevalent in Jammu and Kashmir, Himachal Pradesh, foothills at Hardwar). Today, it is restricted to the Uttarakhand, Nepal and even the northeast, while foothills (Rishikesh-Hardwar).” In the face of high latter two are restricted to Central and East Himalaya. intraspecific competition, especially due to high The Himalayan species live in foothill section density (density-dependent) it seems reasonable for (Sivaliks) of glacierfed Ganga where waters are not individuals to disperse in the vicinity of ideal habitat. ice-cold. The species of Peninsular India inhabit the Large numbers would facilitate dispersal while rivers devoid of glaciers. Mahseer is known migrate decline would restrict the population to the most ideal into small tributaries during the breeding season part of the habitat. Two factors seem to be causing the (Beavan, 1877; Desai, 2003). For the Himalayan decline, over fishing and habitat degradation – mahseer first flooding caused by snowmelt is a signal fragmentation. Hence, when (prior to 1960’s) the for upstream migration into the glacierfed tributaries. Himalayan mahseer occurred in large numbers they The migrants remain in them till the onset of monsoon were able to populate the then Ganga till Narora near when the brooders again ascend into the flooded Aligarh (the last limits of the upper stretch of the spring fed streams for breeding while others Ganga) far downstream of the foothills. But as they (juveniles and adolescents) descend to the foothills. became few they got restricted to the foothills only. The brooders and new recruits (year-old juveniles) Decline has been observed in most of the Indo- © Central Fisheries Research Institute (CFRI) Trabzon, Turkey and Japan International Cooperation Agency (JICA) 126 P. Nautiyal et al. / Turk. J. Fish. Aquat. Sci. 8: 125-132 (2008) Gangetic drainages over the west (Sehgal et al., 1971; exploitation rate and ratio of this species. The Joshi, 1988; Sunder and Joshi 1977; Sehgal, 1994) information is considered a prerequisite for managing and central Himalaya (Shrestha, 1997). the fishery and conservation in case of threatened fish The mahseer are considered as ‘endangered’ species. Hence, investigations were undertaken on (Khan and Sinha, 2000). The decline of the mahseer age, growth parameters, mortality, exploitation rate (T. putitora and T. tor) population in the Lake and ratio. Nainital was mentioned by Raj (1945). Das and Aloka (1978) found biological indicators of pollution in Study Area Lake Nainital and related it to the depletion of Mahseer fish (T. putitora). Das and Upadhyay (1979) All specimens of T. putitora were obtained studied the qualitative and quantitative fluctuations of downstream of Ajeetpur (altitude 273 m; 29°52'50'' N; plankton in two Kumaon lakes, Nainital and Bhimtal 78°10'23'' E) from the Ganga, Raiwala (altitude 340 to determine the causes of the failure of the Mahseer m; 30°3'18'' N; 78°13'54" E) from the Saung, Banghat (T. tor and T. putitora) fisheries in the Kumaon lakes. (altitude 560 m; 29°57'12" N; 78°13'23" E) from the The ‘endangered’ status of the Himalayan mahseer Nayar and Srinagar (altitude 550 m; 30°13'30"; population, however, is debatable as there are still 78°49'39" E) from the Alaknanda (Figure 1). some pockets where this species predominates. The adult population inhabits the foothill stretch Mahseer has kept a steady profile in terms of average of the Ganga and migrates upstream into the Saung size in the reservoirs. For the last 22 years the average and Nayar for spawning. Therefore, these two weight has ranged between 1.2 to 1.6 kg while the tributaries harbour the younger stages and were total landings have fluctuated between 10 to 102 sampled to obtain them. Beside breeding (Sehgal, tonnes during 1995-96 to 1997-98 and the average 1972) there may be other reasons for which the fish weight of mahseer was 1.2 kg (Himachal Pradesh may migrate upstream which may involve factors like Fisheries Department, 2007). The Himalayan mahseer maintaining food supply, homing instinct and learning has been largely studied for natural history, status and by reinforcing memory (Nautiyal et al., 2001). This conservation practices in India and Nepal (Nautiyal, can be explained by the presence of migrants of 1994; Shrestha, 1997). Barring recent attempts to varying sizes (10-137 cm, juveniles, adolescents both investigate the population biology (Bhatt et al., immature, maturing virgins and mature adults) in the 1998a; 1998b; 2000) much remains to be known Alaknanda for 3-4 months (February to June), about the dynamics of T. putitora. FAO has produced whereas the Nayar and Saung largely invite the estimates of population parameters from Nepal brooders (Figure 2). In fact the large size (>80 cm) (Fishbase, 2003). There is no account of mortality and can be obtained only during the migratory phase and Figure 1. The study area of the Gangetic drainage in Himalaya. P. Nautiyal et al. / Turk. J. Fish. Aquat. Sci. 8: 125-132 (2008) 127 were not found in the foothill stretch harbouring the read the ‘key scales’ of T. putitora, obtained from the major part of the mahseer population in the mountain dorsal fin region above lateral line. The annulus section of the Ganga (Nautiyal, 2002). formation was determined according to the criterion suggested by Begenal and Tesch (1978). Materials and Methods Data Analysis Field Sampling The length frequency data obtained at monthly Random samples were obtained from the fish intervals during 1980-81 and 1994-95 were pooled markets, landings sold off locally by fishermen or and finally raised to the annual total catch of the from those procured by the contractor at these species. The growth parameters L∞ and K were stations. At all sites of collection, T. putitora were estimated using the Gulland and Holt (1959) formula: landed using gillnets (7-10 cm mesh size), cast nets and seines. Hook and line was the most effective -∆L / ∆t = K*L∞, method of catching adults. For each fish, total length was recorded to the nearest cm and weight in grams. whereas to was calculated by the von The fish ranged from 4.9 to 137.7 cm during 1980-81 Bertalanffy’s plot. (sample size (n) = 132) and from 4.0 to 135.9 cm The growth parameters computed were used to determine the natural mortality (M) using the methods during 1994-95 (n = 815).